Several studies have shown that the so-called Mediterranean Diet is healthy.
This is not surprising, because as interpreted by various groups, it consists mostly of whole foods instead of a lot of processed junk, and you can show that almost any reasonable diet is healthy if you compare it to the "standard American diet" that is high in trans fat and processed carbohydrates.
Definitions of the diet do differ.
As interpreted by the American Heart Association, the key features of the diet include "high consumption of fruits, vegetables, bread and other cereals, potatoes, beans, nuts and seeds"; emphasis on olive oil in place of other fats; low to moderate consumption of dairy products, fish and poultry, with little red meat, and eggs only zero to four times a week; and low to moderate amounts of wine. They suggest that the diet may have too much fat.
A WebMD article says the Mediterranean Diet features "fresh fruits and vegetables, whole grains, nuts and seeds, legumes, seafood, yogurt, olive oil, and small amounts of wine for heart health."
A New England Journal of Medicine article described the diet as being "rich in vegetables and low in red meat, with poultry and fish replacing beef and lamb," with olive oil and "a handful" of nuts as the main source of fat.
It's clear that different people interpret the "Mediterranean Diet" differently, although they all seem to agree that it is high in vegetables and low in beef. But there are many components to the diet, and it hasn't been clear if the healthy aspects of the diet (for people in general, not necessarily people with diabetes) are because of all the components, some of them, or maybe just one or two.
So when a statistical study of the components of the diet was recently published, showing that some of the Mediterranean Diet components didn't seem to have any effect on mortality at all, I was expecting an avalanche of blog posts commenting on this.
I'm still waiting.
Most of the blog posts and articles I found simply restated what the researchers had reported in their publicity releases, without comment.
The study showed that consumption of cereals, dairy products, and fish had very little effect on the mortality of the participants in the 8-year study in Greece. In fact, in this study, increased fish and seafood consumption slightly increased mortality, although this increase was not statistically significant. But we've been bombarded with messages telling us to eat more "healthy whole grains," fish, and low-fat dairy if we want to be healthy.
Of course, the authors of the study couldn't believe that whole grains aren't healthy, so they suggested that the lack of effect of cereals might be because they didn't separate out processed cereals and whole grains.
It's possible that's true.
It's also possible that when the results of a study don't fit the preconceptions, the authors find some reason to explain it. When the results are what they expect, they accept the study as proof of their pre-existing theories.
The study did show that both low alcohol consumption and high alcohol consumption were associated with a statistically significant increase in mortality compared with moderate alcohol consumption.
They said high consumption of vegetables, legumes, fruits and nuts (which for some odd reasons they lumped together), and olive oil and low consumption of meat and "meat products" (which would included luncheon meats) were associated with reduced mortality.
Then they said that none of these results were statistically significant. This lack of statistical significance is not mentioned in the press releases.
Because the researchers were expecting the results they found for vegetables, legumes, fruits and nuts, olive oil, and meat (although they were not statistically significant), they didn't try to interpret them. For example, "meat" is a broad category. It's possible that some meats such as luncheon meats are unhealthy and other meats such as lean beef are not. Maybe nuts are beneficial but fruits are not, but because they grouped them together, there's no way to know.
Although they called the diet Mediterranean, you notice that all these foods that showed benefit are real, whole foods that hunters and gatherers could eat, rather than processed garbage. You could just as well eat these foods and call it a Whole Foods Diet or a Traditional Diet or a Neolithic Diet. Hunters and gatherers probably eat all the meat they can get, but their hunts are not always successful. Olive oil is processed but in a minimal way. You could get the same monounsaturated fat by eating the olives themselves.
I'm not a big fan of any nutritional studies because most of them are based on food recall forms. I often can't remember what I had for lunch. There's no way I can remember what I ate for the past few days or the past month or so. Nutritional researchers claim they've tested the recall and it's reasonably accurate, but I'm not convinced.
Furthermore, we're all individuals. High fruit consumption might be beneficial for people without diabetes (certainly better than high banana split consumption), but a lot of fruit will raises the blood sugar of people with diabetes.
I suppose this study is a first step. Perhaps future studies will be able to refine these results.
In the meantime, follow the advice we patients so often give. Don't accept any diet as the "best diet" until you see how it affects you individually. If your nutritionist tells you to eat a lot of "healthy whole grains," try a few whole grains and see what it does to your blood glucose levels 1 and 2 hours after you've eaten them.
Then make up your own mind.
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